SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2dc621172223d71addd4a130114886f660fe4bbbcb0bc0bd6295163e7d83e39' 
  AND token = 'VmJarXbKBVbelL9Fi0GjLMeG/mDjyfN86zVQ0JDLVaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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