SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '68572b66854e00443870e51a76825fac7fcf83b07e8b0cd1bac57307c4ae172c' 
  AND token = 'hAZQPh+UyzpZafbYO5urJJLnzE5NkVVDMfk2d+KZmso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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