SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1333257b91a560f368190cca437d573c8f92f4dae11878e72ac856deeb6f757' 
  AND token = '37q9Np1JxWVdAvfvYgDFYn6+5VIE6n8cQfqZKsnrJrc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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