SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '370b03f15771577779116614443182ca54d457f93602168f82898fee140b5b1f' 
  AND token = '6NADQZMQUIWO1UiWEZSvREvd0Mrd20hzsQaqOjda7Yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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