SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f87a4c93a2b1d442fc3b308b28442a13d8ac083d6ad0cc2f5f2aaa2377e3410f' 
  AND token = 'cXhFsJQwvG/uSopTIpGdVH15Ix5YS7Mq+yDAJpKvHJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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