SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5942e35e5dc3fa91b47ae346913ccc75accc6e95625d9dff7be7b7f6f6067246' 
  AND token = 'vrci6j/GZiccOQFmbnTuFpfnjRn4DEcy2elBNxvxCP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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