SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ba74d49f7dc829dc93bf0491ee1963b33688615d4f3c6f3ccc575ce21afa6a2' 
  AND token = 'DOh02kTxFRhvqXtbnnHAhzXFqBGXDP9HJDffRkmZi+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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