SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b96967b0cb1bba277aa01ddbedf80b9fcf58e2865d1637d20baf20215db3b338' 
  AND token = 'VU5LOcTpq9oloF2ndoOaiLSTUh3JmVyzl482LssiDsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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