SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '783c5d35d95d734d192c3fb7bc561d28c261adeae1fb7d09d631762d1b086c66' 
  AND token = 'q5RtLpwhJiBLVLa38FKHLYVNAkVZOf907VNQ3/vwJaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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