SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '272e535ddb3acf12f1a2cff66b9b5edde429c2021371fe2a39ba93c21146081a' 
  AND token = 'y9LTrzCaKRjII5zAKTJGhQUYwT9R1ELJ/TjshB2+V10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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