SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f921d580857ae42a08698d23b5f5e286f6a0b55400e2109cee2e1408bf7119f' 
  AND token = 'iIq0DorLUtMyFspq4DXeOFfCIFamNwFV9UK5+lVXhVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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