SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '4182e1e36e911d56c14a617fdba7c6259abdc886f2275f907950617014ed52dc' 
  AND token = 'nFIS88qHDdg3W85Lzt4czv5oE/pxkdwKUFVw+JLIETI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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