SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad1e5d0d3f594e2c5aa15f04eebdeec63179a52a9932463639636374e4f3854c' 
  AND token = 'SikiPn8MliG0I4Sgsl8YKJgkSEJEL7/XM9zYRToCiF0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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