SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '043f1e2ae2d7c9adafaead344a61aed359577639a459898f80a2b517dc7af044' 
  AND token = '7Gw1EWKbFAq5oYGvFgzZ0rhrKY/eNT1VZRu5ZeUswKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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