SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '234d37a0fea468e5b16641288ca875320fd389f1511b702bdab00f60c6c402ea' 
  AND token = 'GyESk0LJQPMBF5Kxo0qm24XQw9UeiwOnocNixDUrP5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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