SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9d717bf05e35413b82ee51e1b1fc754130f8ced1d4e9aec2b23ae9ef95b6939' 
  AND token = 'rzOnhyI1x+XOEJAXfYfYKSNH9Ptv6mug/VcJ6tKTwJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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