SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68ebd45a644d5152008d4a0909ce9457043fabd7171666c575f2f8906468335f' 
  AND token = 'iV/NqxoIRgxcUcszFOMgXcqBIE8b0GVYYMIU5rjru/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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