SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '83b934f530712ac04074528d01eb0c23716a7d978a6018471cfc2a765e4c26f0' 
  AND token = 'DW72ZSoFFZK3LjGpZaHkRzDmZm6rhBDsSE7mUSss594=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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