SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68f5397ca3d5fd480003e99aa0b96a32a89759cec34f70f409a5b5cd3f668706' 
  AND token = 'pykJ9EPWE6FbeO9C4CMdwVx5zGkMo4AZmV3kVirDu24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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