SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b4e1eb8e5034d1012b10cbc80ed0df7ad1bf7427be6be0b8606183f615eab77' 
  AND token = 'WApG0nhIMDjgmUObbqDiSC+WDckAQKSprYUkvYkM6UM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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