SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8aa49018c272025edb6e4e24a708bcaffbc6af41a371bf35002603e475abffd8' 
  AND token = 'W4UHnrjSOhDLyNAGEiZUsRs1rbTLsuLJNPPHE+svKvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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