SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cafc139750dbfbe7bf4e9f429ea84e492b176fdaff9a4d800f8f7cf2e7e85ac0' 
  AND token = 'q5zF+AdfyclmJWNVN9Oa28nJBLcwp5ZpX0Fq4FHmKI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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