SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '829d895f0c5bd8cc25b58a344532e42bc9acc2e2791e67f884c52675a55f15ec' 
  AND token = 'WJ8ftJLu33E3FOPv/KTqhaxOZXaGswUWLgrKv+lQIPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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