SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4534703ea8c501517afc3802f7e41f0dca593b46bb1ddc348c764ac3dea74f7' 
  AND token = 'U7rBPXEdq5jU2Eqq4cJuXAdZ6c4vuqpwvJBhDRpknOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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