SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '31aeac463941432ad62ed8cd33a82fb3c643c79eadf4bcc25b8a8422871942f5' 
  AND token = 'BdxhnQzEgvvcgXuyWC7PCqMCUoz1BYRBkqv0AlgEQDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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