SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f79841b82183d81b3030948a4636e87740d0587c68661cbb5691993ea852a11d' 
  AND token = '0g7hIvBs0/LyP/xGQp9UqRatoMBLVo+EUwh+yP0WZn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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