SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78f1c0e7e261fd770efbf01cf3ed1d5b75e6d3494537261a62a64a6023271861' 
  AND token = 'SmHVbijibBpA0oVYIvW2mS+spYgBmUEQdTog0FW6l28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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