SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40bd984752a74765a224fb7b4cbeff0974fecc34193688d1d998e7b673e9d536' 
  AND token = 'H5GI1qLn1cOxpon/+e+bnit2mkx9cBA0GYWRe8b4swQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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