SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '16cd0d4e4b7601eb7da9a42655f08d26c2f8e731568b617997f25815c5dde391' 
  AND token = 'J68k4p61Ys+3mLvzZYOpgh2ZMO40xx3E0Bt9SpqGD/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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