SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ced0687d7f060120d13532ceb537aed22a3a52d83c098e529b413be0d1ff970a' 
  AND token = 'PxtwWJNV0UWw5Dy7E/FQ3UKprzFRig1CRuM2STUw9Tg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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