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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e74b9cd4348e70a8ebdbf0f39c42a50b3a97c2069c4efc3446f41181ec4dcf8' 
  AND token = 'JpvL4b3doiZNbeQ2VqBQFt+Yirpvu/r7cr8lDVsZP08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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