SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b87be1921df4504867f55bfb367f19a2cb113b668a99d51cd97dbd0cfbd5b855' 
  AND token = 'KNBVrKa3jCcLlVfnD4p9L9Z+rpbji/76IKr6yx7NQpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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