SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6d207d55018008024f0cdbc8a062136cbaa86c7f48dd966235f693c1814dde2' 
  AND token = 'c7Dz6/RUMUmDgZ/JFGqF6eBJCBWLFdrjKlz8pvqiLss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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