SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b309c339992e26007ddcababf21419e593b10a0892aeb954009e12bd4a3d6bb' 
  AND token = 'GLxn997IvXQpqBBH9mV6xwcDFDRwCxkPryn3BePDHew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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