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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '520126bd9eefb3ea7828e7e0bea4d2ab4b28d9a4aa64a907bfbbaf70bdfee91c' 
  AND token = 'zRAnLyS47ZNwQcaL2PzyR3/9kvuScMM8LAGCCaSqwzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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