SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '973bb2850dc4da60df59a223b1e53780c485e0dd723149863b249bcf978322b5' 
  AND token = 'oBXqDSj1jsw+Fa+ZkMv+aNGBmwAGZEDMc65OfpLzJBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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