SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21fef51d085ca1c670c8cc5d173d6a8c3c4bd84eb29acaa9b374121a9c4cfd2c' 
  AND token = 'xtemEoPOvohyC6fGzFoXnhR2KnjmqyNBMOYJ7l6Tolw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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