SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '175ac0366862351b3cc9dd91d04c3ccc7db6d00799f871b88c8817ad4bf4d926' 
  AND token = 'eTQmKjHx507fQlOCsynCm5kZ+x+SQtfiAlTK+7ENlkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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