SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f4d6cc4c85cbabcae35be89a0378ea886946e9917295371818ad9506e81c7f2' 
  AND token = 'CT85PeZlW2FHUYj7mVHkiJxjMeln6li0dE4P3zJhMR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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