SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd07555fe13f1942db3f23945e8d7f6ecafbc71b2e9c179262636d91da14b6c88' 
  AND token = '/8fldwz5sW5Wuj+VN9Q3u6FLlyTh5cDbGV88vkmYDr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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