SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a996405f0cf283ec28aec914982bdb583702a7f060153d1870bd05b69bae743f' 
  AND token = 'Bm2o/ENb8jf7fgdbMxVXumNBsMPXn3cHZXNVJjuzvz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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