SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79b12b981dd4a18e575d571cc1f620f3855bfd7627a939398038424549b9c5d0' 
  AND token = 'qdydBCswgP+1H6UErGY+yUoAxIJBf4J+2+qgD/rctCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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