SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '496fb1ca67171648e2b270d0f146e680c719e1dc5121e44ae29394dd24427359' 
  AND token = 'NmoLG71MB+JQgkAU1ALMsykk0Et1eGaeObZOeL78PRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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