SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a890a113b1293bf20d1ddfefa8c17b4aa0c9515350eb2457f6bc947a24a3b79c' 
  AND token = 'Nc7aXIUqdRoyWxdBP1I0PqEuB0/6sHkAyVBaBn9Aszc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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