SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '07b8278ffd21da99422b1d5e3bcfe43f934a3cba3b2023bd2ae4809d582a6145' 
  AND token = 'mKbyWL47v+FfnwSHfHi7AxNRmxOLXjTeoOqUel1y+OQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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