SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '310404cdf0415bfe637b5a50cf9065041714ccf58cac44735f2888e543a948dc' 
  AND token = 'M1Zd1ww9CQYJkbooTLrNuiQ7GxauFpVzr0rXVC/DvWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00070

JSON explain

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