SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f50f4b09dacdc8403c63185df568e95080ea73a89012926c879ea509f120c814' 
  AND token = 'Uipe5Ej6mzyaxMeGe8RHm7Sa7Wqu43DQsHzOwdaO6T0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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