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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42bf7cdbcc70c4243959a26edfb9b8c3eb699c5aecd83dca2479a5bc45ff3b7c' 
  AND token = 'pUGxtzbiQOqNpJkDs3GBGJkqSyGzI+rO6s8HZQgiE9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}