SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b55320113a132f5ce4480fd2027a8e0633c70ad8de91ed37d8253d2fdda357c' 
  AND token = '3Wk0RF1JCNxxYMESUak1ppPnHVNsn9vKBr4eIaUTTkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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