SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75c192c79337dc592b4a1a6cd8087d672cf28841d27d2abb0a0e19fe9ee187f9' 
  AND token = 'D8UVXnoBX3p+j9F/AkiuC/G0kqg/ECwKDXCp7Q5hXy0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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