SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2f6ce0638d56112ec96a8dea9c68cdc1781268bfd45e538cc1738e6e8e63a62' 
  AND token = 'OUcUKjX8PsO6qXfWhCCmFcdPfwnxCDrKf5hogiVNqW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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