SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fe031edca09a9ac7459fba438a1a8d8dbe478488edeeb4214242368e748ad05' 
  AND token = 'F6plpSUKMPYONCmfKgzT+VMhJs7rl3bXRn+YSWksWPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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