SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c468ec45621a9eb88093556b82d82c56ebf886c4a1079b7b1c32587bc9770828' 
  AND token = '8havY2dUrvwhe+WbsyRo4JldPctrTAeeLOjX3YFWjeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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