SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5a97331635cf1b3a14d54308ab0056d6209e3d1bd6e34c65840126291afe5e2' 
  AND token = 'Ye7Wcd0na7cSrf8uKxnYJgT2jHEB5PjNDnAMQ3A5iiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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