SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5eb265956a6657dc1a047f5fec23bf4f755941e4b655c8339e680deebf4bc97' 
  AND token = 'qPr7mgOkEuK4XowXKAkqMWIQq8/17figA0aXGrMfXoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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