SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f2c5243f380927a36374c85d9d7be52a59612daad2c31301780dae690a20756b' 
  AND token = 'BtPRsOg4osQmtMahsru1kxLJn3mn6zrDdYJoRlHYBPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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