SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '247b6edc3ac87dc2483c907fe44f8f6289382af7df46f82b93ff3afb9858ddcf' 
  AND token = 'SFAOjxnLYjZrgWdf7Q+V9ax5psfXWiiLXoq5nCMCkbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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