SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3935e2c4500dcc4cfa9c2b960e1c52b400397b976f518558e7e89e08460cbcb4' 
  AND token = 'VtizsAeFHdm6QqcfsKT3WDeUuOrs7Tn2+ScXwxT3eSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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