SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f52d12428028c27f238d2c7402595f39b6bfdf8767b608e640912f3274245f1a' 
  AND token = 'FG723OVSZDlTNtytPFp2itILV2VqnoEbDfGARQQYECg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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