SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b4cf0076f8700bb9a588146f3c7d30d2ef0e0e95c06719c70f526d926def6d3' 
  AND token = 'vCgdJW0aUu0CKb8bZmJHw8BQcf5vIcyEKNBgaqaShOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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