SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e78aa48db48ea289812066a06d0208453a35cea91e1d7b53b60d633c42895ebd' 
  AND token = 'yLSjqMVi3wZLqA/JdE3kEjevh1opHdQy2uRzPkmR4VM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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