SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16b380c9e44a317852a8d375e60b30ee99d546720d9a4124576f018477ce5942' 
  AND token = '8hHzwBscjrYG/501nnwqfIl5tVw+NBFqxB3+OkEEULo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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