SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12e6bc3f1de5fddca66757d2e883c24d493e75a8190286e7ec29ab25130bdde9' 
  AND token = 'TOjrlzKKz2gPjtNvcHl148u60g347bRbcuoHw+NG3UM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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