SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f323197fcb69ee15a6e789baaae9354d7794a562fb0986afaa854e7e3b8fc27d' 
  AND token = 'LCCaqa4uUuylgygGslSTQor6tl1vmmPBtm+jexDI3vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}