SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b42f434ea5d536f4eba90b2f918e4467b2afb730271635d8a03cb0c53d650c94' 
  AND token = 'X3LWkNsgIFPYyft/Y3ozpYl9jvhK7Icxi2mBnJuEQow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}