SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c699f83b439637792aa24af67e932303c881de5b803daa495186572f3d75abd' 
  AND token = 'jW07SKjfXtgfuyGGaWzrS4oKqmppzl+wsZOS20kP1j4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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