SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2bea5b63878cbae438c41b5531d872750f133d4e705d387ac066e58dbcc6c4a6' 
  AND token = 'kvvGj1vW6XDoYjeOvtLRTHumcFl8ION3UmtRHj0Xln4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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