SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb008ef799c1bd044186336249406ddce161b8642a412fc84a7e7271c3307c66' 
  AND token = 'e/KsKh2RAExql0KJ6yAPb+FUvQBi04TjOYpN7HmCHQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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